- AuBr3-catalyzed [4 + 2] benzannulation between an enynal unit and enol
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The reaction of enynals 1, including o-alkynylbenzaldehydes, and carbonyl compounds 2 in the presence of a catalytic amount of AuBr3 in 1,4-dioxane at 100 °C gave the functionalized aromatic compounds 3 in high yields. The AuBr3-catalyzed formal [4 + 2] benzannulation proceeds most probably through the coordination of the triple bond of 1 to AuBr3, the formation of a pyrylium auric ate complex via the nucleophilic addition of the carbonyl oxygen atom, the reverse electron demand-type Diels-Alder addition of the enols, derived from 2, to the auric ate complex, and subsequent dehydration and bond rearrangement. Similarly, the AuBr3-catalyzed reactions of 1 with acetal compounds afforded the corresponding aromatic compounds in good yields. Copyright
- Asao, Naoki,Aikawa, Haruo,Yamamoto, Yoshinori
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- Lewis acid-catalyzed [4 + 2] benzannulation between enynal units and enols or enol ethers: Novel synthetic tools for polysubstituted aromatic compounds including indole and benzofuran derivatives
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The reaction of enynals 1, including o-(alkynyl)benzaldehydes, and carbonyl compounds 2, such as aldehydes and ketones, in the presence of a catalytic amount of AuBr3 in 1,4-dioxane at 100 °C gave the functionalized aromatic compounds 3 in high yields. Similarly, the AuBr3-catalyzed reactions of 1 with acetal compounds 5 afforded the corresponding aromatic compounds 3 in good yields. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(NTf2)2 and 1 equiv of H2O in (CH2Cl)2 at 100 °C, the decarbonylated naphthalene products 4 were obtained selectively over 3. Benzofused heteroaromatic compounds, such as indole derivatives 13 and benzofuran derivatives 15, were also synthesized by using the present benzannulation methodology.
- Asao, Naoki,Aikawa, Haruo
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- Divergent Synthesis of Highly Substituted Pyridines and Benzenes from Dienals, Alkynes, and Sulfonyl Azides
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Divergent synthesis is extremely important for the highly efficient preparation of structurally diverse target molecules. Herein, we describe a multicomponent cascade reaction, which allows access to highly substituted pyridines and benzenes by combining four individual steps in a one-pot manner from the same set of readily available starting materials. The azepine intermediates were first used as the precursors for 6π-electrocyclization to construct highly substituted pyridines and benzenes in a tunable manner.
- Luo, Han,Li, You,Du, Luan,Xin, Xiaolan,Wang, Tao,Han, Jingpeng,Tian, Yi,Li, Baosheng
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supporting information
p. 7883 - 7887
(2021/10/20)
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- New Nickel-Based Catalytic System with Pincer Pyrrole-Functionalized N-Heterocyclic Carbene as Ligand for Suzuki-Miyaura Cross-Coupling Reactions
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A new catalytic system with Ni(NO3)2·6H2O as the catalyst and a pincer pyrrole-functionalized N-heterocyclic carbene as the ligand was employed in the Suzuki-Miyaura cross-coupling reactions of aryl iodides with arylboronic acids. With 5 mol% catalyst, the catalytic reactions proceeded at 160 °C, giving coupling products in isolated yields of up to 94% in short reaction times (1-4 h). The system worked efficiently with aryl iodides bearing electron-donating or electron-withdrawing groups and arylboronic acids with electron-donating groups. Steric effects were observed for both aryl iodides and arylboronic acids. It is proposed that the reactions underwent a Ni(I)/Ni(III) catalytic cycle.
- Guo, Zhifo,Lei, Xiangyang
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supporting information
(2021/09/11)
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- Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
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Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
- Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
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supporting information
p. 8796 - 8801
(2020/11/13)
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- Palladium-Catalyzed Amide N-C Hiyama Cross-Coupling: Synthesis of Ketones
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N-Acylglutarimides and arylsiloxanes reacted in the presence of Pd(OAc)2/PCy3, Et3N·3HF, and LiOAc to provide the corresponding arylketones in good yields. Aryl-, vinyl-, and alkyl-substituted N-acylglutarimides showed good activity in the coupling reactions of arylsiloxanes. The reaction had a broad substrate scope and showed good functional group tolerance. N-Benzoylsuccinimide and N-protected N-phenylbenzamides showed good activities in coupling reactions with phenylsiloxane. The employment of CuF2 as an activor afforded the decarbonylative products at 160 °C.
- Idris, Muhammad Aliyu,Lee, Sunwoo
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supporting information
p. 9190 - 9195
(2020/11/18)
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- 6-Arylphenanthridines from Aryl o-Biaryl Ketones with 1,1,1,3,3,3-Hexamethyldisilazane and Molecular Iodine
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Warming treatment of aryl o-biaryl ketones with 1,1,1,3,3,3-hexamethyldisilazane in the presence of Sc(OTf)3 in toluene, followed by the reaction with molecular iodine and K2CO3 in a mixture of THF and methanol at 60 °C gave the corresponding 6-arylphenanthridines in good to moderate yields. The present reaction is a one-pot method for the preparation of 6-arylphenanthridines from aryl o-biaryl ketones through the cyclization of imino-nitrogen-centered radicals that were generated from N-iodo aryl o-biaryl ketimines formed from the reaction of aryl biaryl ketimines with molecular iodine.
- Kobayashi, Eiji,Kishi, Atsushi,Togo, Hideo
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p. 7335 - 7347
(2019/11/22)
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- Ruthenium(0)-Catalyzed Cross-Coupling of Anilines with Organoboranes by Selective Carbon-Nitrogen Cleavage
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Selective activation of neutral carbon-nitrogen bonds is of great synthetic importance, because amines are among the most prevalent motifs across organic and bioactive molecules. Herein, we report the Ru(0)-catalyzed selective cleavage of neutral C(aryl)-N bonds in generic aniline derivatives enabled by a combination of Ru3(CO)12 and an imino auxiliary. These mild conditions provide a direct route to high-value biaryl ketones and biaryl aldehydes after facile in situ hydrolysis. A broad range of organoboranes and anilines can be coupled with high C-N cleavage selectivity. Most crucially, the reaction achieves exquisite selectivity for activation of C(aryl)-N bonds in the presence of typically more kinetically favorable C(aryl)-H bonds. The method provides a strategy for the construction of functionalized terphenyls by exploiting orthogonal properties of the Ru(0) catalyst system and traceless nucleophilic properties of anilines.
- Zhao, Qun,Zhang, Jin,Szostak, Michal
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p. 8171 - 8177
(2019/08/22)
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- AMINE COMPOUND AND ORGANIC ELECTROLUMINESCENCE DEVICE INCLUDING THE SAME
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An amine compound and an organic electroluminescence device including the same are provided. The amine compound according to an embodiment of the inventive concept is represented by Formula 1.
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Paragraph 0102; 0103
(2018/10/21)
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- Palladium-catalyzed Suzuki-Miyaura coupling of aryl esters
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The Suzuki-Miyaura coupling is among the most important C-C bond-forming reactions available due to its reliability, chemoselectivity, and diversity. Aryl halides and pseudohalides such as iodides, bromides, and triflates are traditionally used as the electrophilic coupling partner. The expansion of the reaction scope to nontraditional electrophiles is an ongoing challenge to enable an even greater number of useful products to be made from simple starting materials. Herein, we present how an NHC-based Pd catalyst can enable Suzuki-Miyaura coupling where the C(acyl)-0 bond of aryl esters takes on the role of electrophile, allowing the synthesis of various ketone-containing products. This contrasts known reactions of similar esters that provide biaryls via nickel catalysis. The underlying cause of this mechanistic divergence is investigated by DFT calculations, and the robustness of esters compared to more electrophilic acylative coupling partners is analyzed.
- Halima, Taoufik Ben,Zhang, Wanying,Yalaoui, Imane,Hong, Xin,Yang, Yun-Fang,Houk, Kendall N.,Newman, Stephen G.
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supporting information
p. 1311 - 1318
(2017/05/16)
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- Inherent vs Apparent Chemoselectivity in the Kumada-Corriu Cross-Coupling Reaction
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The Kumada-Corriu reaction is a powerful tool for C-C bond formation, but is seldom utilized due to perceived chemoselectivity issues. Herein, we demonstrate that high-yielding couplings can occur in the presence of many electrophilic and heterocyclic functional groups. Our strategy is mechanically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard reagent. The mechanistic reason for the effectiveness of this strategy is uncovered by continuous-infusion ESI-MS studies.
- Hua, Xiye,Masson-Makdissi, Jeanne,Sullivan, Ryan J.,Newman, Stephen G.
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supporting information
p. 5312 - 5315
(2016/11/02)
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- Dual role of acetanilides: Traceless removal of a directing group through deacetylation/diazotation and palladium-catalyzed C-C-coupling reactions
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The acetamide group enables regioselective oxidative ortho-C-H activation reactions, such as Pd-catalyzed acylation. The synthetic utility of these transformations can be significantly enhanced by using the acetamide as a quasi-leaving group in a subsequent conventional Pd-catalyzed coupling or cross-coupling reaction. The concept is illustrated herein for the synthesis of o-alkenyl- and o-arylphenones, which have potential for the synthesis of arylated aromatic heterocycles.
- Schmidt, Bernd,Elizarov, Nelli,Schilde, Uwe,Kelling, Alexandra
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p. 4223 - 4234
(2015/05/13)
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- Stereoselective synthesis of folded luminogens with arene-arene stacking interactions and aggregation-enhanced emission
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Tetraphenylethene derivatives with a folded Z-conformation and aggregation-enhanced emission characteristics are synthesized from 2-arylbenzophenones. The intramolecular rotation of the folded luminogens is partially suppressed, resulting in improved emission efficiencies in solutions.
- Zhao, Zujin,He, Bairong,Nie, Han,Chen, Bin,Lu, Ping,Qin, Anjun,Tang, Ben Zhong
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supporting information
p. 1131 - 1133
(2014/01/17)
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- Selective Co/Ti cooperatively catalyzed biaryl couplings of aryl halides with aryl metal reagents
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Various aryl bromides or chlorides, including those bearing a free COOH, OH, CONHR, and SO2NHR group, coupled with aryl magnesium or lithium reagents in the presence of 7.5 mol % CoCl2/15 mol % PBu3 and substoichiometric Ti(OEt)4 (40 mol % to ArM) at room temperature in high yields with high chemo- and regioslectivity. This simple reaction represents the first example of Co/Ti cooperative catalysis which plays a key role in suppressing undesired homocouplings.
- Zeng, Jing,Liu, Kun Ming,Duan, Xin Fang
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supporting information
p. 5342 - 5345
(2013/11/06)
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- Suzuki-Miyaura cross-coupling of aryldiazonium silica sulfates under mild and heterogeneous conditions
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An efficient and straightforward procedure for the Suzuki-Miyaura cross-coupling reaction was studied by using aryldiazonium silica sulfates and sodium tetraphenylborate in the presence of a catalytic amount of Pd(OAc) 2. These reactions were carried out in water at room temperature without using additional ligands.
- Zarei, Amin,Khazdooz, Leila,Hajipour, Abdol R.,Rafiee, Fatemeh,Azizi, Ghobad,Abrishami, Fatemeh
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experimental part
p. 406 - 408
(2012/02/02)
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- Copper catalyzed Gomberg-Buchmann-Hey reaction using aryldiazonium tosylate
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Copper catalyzed modification of Gomberg-Bachmann-Hey reaction to synthesize symmetrical/unsymmetrical biaryls via diazotization of anilines with p-TSA and NaNO2 system at 50 °C, in aromatic liquids as solvents and second partners was successfully developed. Aniline and 3-nitronaniline gave biphenyl and 3-nitrobiphenyl, respectively, with moderate yields. All para-substituted anilines gave comparatively higher yields while in the other cases including ortho-substituted anilines yields were lower. Except anilines with o-NHCOCH3 and o-CONH2 which gave symmetrical biaryls, all others gave selectively unsymmetrical biaryls.
- Chaturbhuj, Ganesh U.,Akamanchi, Krishnacharya G.
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experimental part
p. 4950 - 4953
(2011/10/08)
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- Fluorenone synthesis by palladacycle-catalyzed sequential reactions of 2-bromobenzaldehydes with arylboronic acids
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Chemical equations presented. A new, anionic four-electron donor-based (type I) palladacycle-catalyzed sequential reaction of 2-bromobenzaldehydes with arylboronic acids based on the addition reaction, cyclization via C-H activation-oxidation sequence is described. Our study provided an efficient access to a variety of substituted fluorenones/indenofluorenediones from readily available arylboronic acids and 2-bromobenzaldehydes.
- Liu, Tao-Ping,Liao, Yuan-Xi,Xing, Chun-Hui,Hu, Qiao-Sheng
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p. 2452 - 2455
(2011/06/25)
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- Umpolung direct arylation reactions: Facile process requiring only catalytic palladium and substoichiometric amount of silver salts
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An umpolung direct arylation process is described. The reaction requires only a catalytic amount of Pd(OAc)2 and a substoichiometric amount of silver salts, without any external base or ligand to proceed. The directed oxidative insertion of the transition metal followed by the coupling into the C-H bond of an unactivated arene has surprisingly not yet been reported, despite the clear advantages in the ease of starting material synthesis. The reaction is regioselective with regards to the arene partner, and the role of the acetate and carbonate groups has been elucidated. This methodology adds to the very few examples of benzene coupling without the inclusion of electron-withdrawing groups to increase acidity.
- Mousseau, James J.,Vallee, Frederic,Lorion, Melanie M.,Charette, Andre B.
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supporting information; experimental part
p. 14412 - 14414
(2010/12/24)
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- An efficient MnCl2-catalyzed tandem acylation-cross-coupling reaction of o-halobenzoyl chloride with diorganyl magnesium compounds
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An efficient tandem cross-coupling reaction of o-chlorobenzoyl chloride with dialkyl and diaryl magnesium compounds in the presence of manganese (II) chloride was developed, which proceeds in good yield under mild conditions. Copyright
- Zhang, Fengmin,Shi, Zhuangzhi,Chen, Feng,Yuan, Yu
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experimental part
p. 57 - 63
(2010/10/21)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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supporting information; experimental part
p. 11908 - 11916
(2009/04/06)
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- IRON OR COBALT-CATALYZED CARBON-CARBON COUPLING REACTION OF ARYLS, ALKENES AND ALKINES WITH COPPER REAGENTS
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The invention relates to a method for combining carbon-carbon bonds starting from a copper compound of an aryl, heteroaryl, alkene or alkine and an aryl, heteroaryl, alkene or alkine compound with a suitable nucleofuge. The copper compounds can be produced inter alia by transmetallization from a Gignard or lithium compound. The cross-coupling of said compounds is carried out with a halogen-substituted aryl compound with the aid of an iron or cobalt catalyst using a suitable solvent and suitable additives.
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Page/Page column 12-13
(2010/11/08)
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- Cobalt-catalyzed cross-coupling reactions of heterocyclic chlorides with arylmagnesium halides and of polyfunctionalized arylcopper reagents with aryl bromides, chlorides, fluorides and tosylates
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A range of aromatic organocopper or organomagnesium compounds undergo smooth cross-coupling reactions with aryl bromides, chlorides, fluorides and tosylates, leading to polyfunctionalized aromatics or heterocycles in the presence of cobalt salts (5-7.5 mol%) as catalysts. Very mild reaction conditions are needed and, in the case of cross-coupling with organocopper compounds, Bu4NI (1 equiv) and 4-fluorostyrene (20 mol%) are essential as promoters for successful couplings. Georg Thieme Verlag Stuttgart.
- Korn, Tobias J.,Schade, Matthias A.,Cheemala, Murthy N.,Wirth, Stefan,Guevara, Simon A.,Cahiez, Gerard,Knochel, Paul
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p. 3547 - 3574
(2008/03/14)
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- Iron-catalyzed aryl-aryl cross-couplings with magnesium-derived copper reagents
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(Chemical Equation Presented) Well-matched couples: Functionalized aryl and heteroaryl copper species obtained from the corresponding magnesium derivatives undergo Fe-catalyzed cross-coupling reactions with aryl iodides that bear keto, ester, triflate, or nitrile groups (see scheme).
- Sapountzis, Ioannis,Lin, Wenwei,Kofink, Christiane C.,Despotopoulou, Christina,Knochel, Paul
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p. 1654 - 1657
(2007/10/03)
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- Cobalt(II)-catalyzed cross-coupling of polyfunctional aryl copper reagents with aryl bromides and chlorides
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(Chemical Equation Presented) Polyfunctionalized biphenyl and heteroaromatic compounds were formed in the presence of [Co(acac)2], Bu4Nl, and 4-fluorostyrene (3) through a smooth cross-coupling reaction between organocopper reagents 1, prepared by the transmetalation of functionalized aryl magnesium halides with CuCN·2 LiCl, and aryl halides 2 that bear electron-withdrawing substituents. acac = acetylacetonate, DME = 1,2-dimethoxyethane, DMPU = 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone.
- Korn, Tobias J.,Knochel, Paul
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p. 2947 - 2951
(2007/10/03)
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- Unexpected cross-coupling reaction between o-chloroaryl ketones and organomanganese reagents
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(Chemical equation presented) Alkyl- and arylmanganese reagents react with o-chloro or o-bromoaryl ketones to give the substituted ketones in high yields. The cross-coupling reaction is performed under mild conditions (-60 to +40°C, 30 min to 4 h) and tak
- Cahiez, Gerard,Luart, Denis,Lecomte, Fabien
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p. 4395 - 4398
(2007/10/03)
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- Intramolecular reactivity of arylcarbenes: Biphenyl-2-ylcarbenes
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Biphenyl-2-ylcarbenes, 2-ArC6H4CR, were generated photolytically and thermally from diazo precursors. Cyclization, leading to fluorenes, competes with capture of the carbenes by methanol but proceeds faster than intramolecular hydrogen shifts (with R = Me) and intermodular C - H insertion reactions (with R = H in cyclohexane). By comparison of product ratios with kinetic data for related carbenes from the literature, the cyclization rate is estimated as ca 1011 s-1. The intramolecular reactivity of biphenyl-2-ylcarbenes is not significantly attenuated by variation of R (R = H, Me, Ph). Very minor effects of triplet sensitization and methanol quenching indicate that fluorenes arise from spin-equilibrated biphenyl-2-ylcarbenes, presumably from the singlet state. When Ar = mesityl, the carbene predominantly inserts into C - H bonds of the 2′-methyl groups, giving rise to a dihydrophenanthrene. Formation of a fluorene derivative, by formal insertion into C - C bonds, occurs as a minor process. This unprecedented reaction points to intervention of an o-xylylene in which the methyl group migrates. Laser flash photolysis (LFP) of 2-PhC6H4CN2Ph generates a transient absorption which is due to the T0→Tn transition of 9-phenylfluorene rather than to the presumed o-xylylene. On LFP of 2-ArC6H4CN2Ph in trifluoroethanol-acetonitrile, protonation of the carbenes gives rise to carbocations, 2-ArC6H4CH+Ph. The transient absorption spectra of these cations are strongly influenced by twisting about the Ar - Ar bond (Ar = Ph 4.
- Dorra, Michael,Gomann, Klaus,Guth, Michael,Kirmse, Wolfgang
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p. 598 - 610
(2007/10/03)
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- Aroyl Peroxides. Part 7. The Effects of Additives on the Thermolysis of Aroyl Peroxides in Arenes and the Elimination of Possible Complications in the Measurement of Partial Rate Factors for Phenylation
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Competitive homolytic arylation of arenes has been carried out under conditions in which biaryl formation is maximised.Improved yields of biaryl were obtained with o-chloroanil, nitro- and nitroso-compounds, and transition metal salts; nitrosobenzene, pentafluoronitrosobenzene, copper(II)benzoate, and iron(III)benzoate caused nearly theoretical yields of biaryl and aroic acid.Partial rate factors, measured under such conditions, are free from uncertainties arising from the selective removal of ?-complexes by side-processes such as dimerisation.The possibility that arenes form complexes with aryl radicals or their precursors as a necessary part of the selection process between substrate molecules was not confirmed in studies of the application of the additivity principle and of the multiplication rule, and of variation in the relative concentration of the two competing arenes.The absence of any discrepancies indicates that the measured partial rate factors are not influenced by such putative complex formation.The mechanism of action of these catalysts has been investigated.
- Bolton, Roger,Dailly, Bryce N.,Hirakubo, Kazuko,Lee, Kong Hung,Williams, Gareth H.
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p. 1109 - 1120
(2007/10/02)
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- Photolysis of Alkyl Azides. Evidence for a Nonnitrene Mechanism
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The photolyses of nine sec- and tert-alkyl azides have been studied in detail.The products consist of imines derived from 1,2-shifts of groups on the alkyl carbon atom α to the azide nitrogen atom.No evidence of typical nitrene processes (aromatic substitution, aliphatic C-H insertion) was found.The imine product distributions are rationalized on the basis of a preferred migration orientation in the photochemically excited azide, along with a consideration of either ground or excited state rotational equilibration of the azide.Photolyses of selected azides carried out over an approximately 200 deg C temperature range allow an estimation of apparent activation energy differences between different group migrations.These energy differences are in the range of 70-493 cal/mol and are related to rotational equilibration of the alkyl azide.
- Kyba, Evan P.,Abramovitch, Rudolph A.
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p. 735 - 740
(2007/10/02)
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